Floaters & Flashes

Floaters are extremely common and therefore considered to be a very normal occurrence. In fact, they are so common that approximately two thirds of the general population will have floaters by the time they reach their mid-60s. However, they can occur at any age. When they first appear, it’s typically only in one eye but sometimes they may present in both eyes at the same time. It is also important to note that when they do present the person in question may report flashes of light in their vision as a result.

What do floaters look like?

Floaters can take on any number of appearances and will always be described differently from one person to the next. However, they are usually observed as being either ‘dots’, ‘blobs’, ‘lines’, ‘twigs’, ‘worms’, ‘hairs’ or even ‘cobwebs’ in some instances. They will move around inside the eye, with this movement being exacerbated by the person’s own eye movements, and tend to be most visible when viewed against a light and uniform background (e.g. a white wall or looking out of a window). They can vary in size and although you may be more aware of them at certain times (which can be a nuisance!), the brain does generally learn to ignore them.

What causes the floaters?

Floaters are typically caused as a result of a process called vitreous syneresis/liquefaction. The vitreous [humour] is the name given to the gel that fills the main cavity of the eye and is attached to the retina (i.e. the light-sensitive layer at the back of the eye) at various points. Some of these adhesions are stronger than others.

As we get older, typically after 50 years of age, the vitreous contracts and becomes less like a gel and more like a liquid. When this happens, holes can develop in the vitreous bag allowing liquefied vitreous to escape into the space between the vitreous bag and the retina. Floaters are essentially the shadows of the escaped collagen fibres that are cast on the retina during this process, hence why we see them.

As part of this process, the liquefied vitreous that fills the space between the vitreous bag and the retina naturally causes the vitreous to detach from its points of adhesion to the retina. This is referred to as a Posterior Vitreous Detachment (PVD) and is a common cause of more/larger floaters becoming visible in a person’s vision. It is this that can also be associated with flashes in the person’s vision.

What causes the flashes?

When the vitreous detaches from the retina, as described above, if there is a point where the vitreous is still adhered to the retina then the tractional pulling or tugging on the retina that results can cause the person to experience a flash of light in their vision. This is typically observed as being vertical streaks of lightning/fireworks to the side of the vision in one eye (as a PVD only tends to occur in one eye at a time) and so is considered to be separate to what would occur with classical migraine. Similarly, if flashes in the context of a PVD are going to occur then it is almost always in conjunction with floaters and not in isolation. Once a PVD is complete, the tractional force exerted on the retina is released and the flashes stop. This can in some cases take up to 4 – 6 weeks from onset.


Why do I need to have my eyes examined if I have a sudden onset of floaters and/or flashes?

If there is a strong adhesion between the vitreous and the retina, the force that is exerted can sometimes cause a break in the retina (i.e. a retinal tear/hole). This can then allow the liquefied vitreous to gain access to the space underneath the retina and potentially cause a retinal detachment. A detached retina can cause a loss of vision and requires a surgical procedure in order to put the retina back where it needs to be. This is why it is of the utmost importance that you get your eyes examined as soon as possible after the onset of your symptoms.

The symptoms to look out for (typically occurring in one eye only) are:

  • A sudden increase in floaters (especially if accompanied by flashes)
  • A new and large floater that has not been noticed before
  • A change in any floaters and/or flashes following trauma to the eye
  • A shadow/curtain/veil spreading across the vision in the eye

 

In order to examine the affected eye sufficiently, the pupil will need to be dilated using drops. These drops can affect your vision for a few hours which is why it is always best that someone else drives for you in these circumstances.

Who is at risk of retinal detachment?

Unfortunately, some people are at more risk of developing a retinal detachment than others. These tend to include:

  • People over the age of 50 years
  • People who have had previous surgery on the eye (e.g. cataract)
  • People who are myopic or short-sighted (i.e. corrected with a minus prescription)
  • People who have had previous trauma to the eye
  • People who have a history of retinal detachment in their family
  • People who have had a previous retinal detachment in the same or other eye

 

Should I be worried about floaters?

Floaters are generally innocuous and so there is no need to worry if you have them. However, if, as outlined above, you suddenly notice more floaters in your vision and/or a larger floater that was not there before, especially if accompanied by flashes of light, then you must contact your optometrist as a matter of urgency. By having your eyes examined as soon as possible after onset, if there is any problem observed then it can be managed promptly before it progresses into something more serious.

If you have any queries or concerns about floaters and flashes then please do not hesitate to contact us.

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